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Fuel Economy in Hot Weather

Many drivers have their own techniques for getting better gas mileage, but they are often ineffective. In fact, one of the easiest ways to improve fuel economy is simply to drive in hot weather. But why does it help? And how can you make sure you’re improving your fuel economy in hot weather?

Engine and Gasoline

When it’s particularly cold outside, you may need to warm your car up for a minute or two before heading to work in the morning. But when it’s hot outside, your car warms up very quickly, which means you don’t have to spend as much time idling to warm your car up. And when you’re idling, you’re getting zero MPG.

Your gasoline also plays a part in hot weather fuel economy. When you purchase gas in the summer, it actually has a slightly different formula than winter gas. This is because the Environmental Protection Agency requires distributors to use a slightly reformulated gas during the summer months in major cities. Because of this slightly different formula, the gas you buy in the summer has slightly more energy.


Aerodynamic drag can be one of the main causes of substandard fuel economy. If you look at the shape of most cars, you’ll notice they have a similar cut that is designed to reduce wind resistance and improve speed and fuel economy. But when you drive with your windows all the way down, outside air has to come through your windows rather than traveling over the car, which can cause significant wind resistance and reduce mileage.

So why is this better in the summer? There are two reasons. For one, warm air creates less drag than cold air when it passes over your vehicle. Changes in driving habits during the summer also contribute to reduced aerodynamic drag. When it gets too hot outside, many people will opt for AC over rolling the windows down, which can help fuel economy in some cases. On the contrary, using the AC places a load on the engine while running, which may decrease fuel economy

Tips To Improve Gas Mileage

So, what can you do to ensure you’re taking advantage of the improved fuel economy that summer has to offer? By following these tips, you can get the most out of every tank of gas this summer:

  • Roll your windows down when you’re driving slowly. This minimizes aerodynamic drag and helps you avoid overusing the AC, which should only be used at higher speeds that would cause drag.
  • Keep your AC use to a minimum. When used for long periods of time, air conditioning can reduce fuel economy by as much as 25 percent.
  • To reduce the need for AC, park in shady spots to keep your car cooler.
  • Before you use the AC, roll the windows down for a few minutes to let all of the hot air escape from the cabin.
  • Don’t use AC while you’re idling. If you’re going to turn your AC on, wait until you’ve driven off and properly aired out the cabin.
  • Check your owner’s manual for any tips on improving fuel economy when using the AC. There may be recommended settings that provide a balance of comfort and savings.
  • If you drive a hybrid or electric vehicle, you can cool the cabin while it’s plugged in to charge so you don’t have to use your battery for cooling.

Keep in mind that hot weather doesn’t always boost your mileage — you have to drive properly and cut down on your air conditioning use. Keeping your windows down on the highway or overusing AC will actually lead to a decrease in fuel economy. But if you follow some of these tips properly, you can reduce your monthly gas expenses.